The Skeleton

Two Divisions

• Axial

• Appendicular

Axial Skeleton

The “axis” of the Body

• Skull

• Inner ear bones

• Hyoid Bone

• Rib cage

• Vertebral column

Axial Skeleton Functions

• Framework for supporting and protecting organ systems in dorsal and ventral body cavities

• Surface area for muscle attachment– Head, neck and trunk stability and movement– Respiratory movement– Stabilize/position appendicular skeleton

Skull• Protect Brain

• Support sense organs– Vision– Hearing– Balance– Olfaction– gustation

Skull

• 22 bones– 8 cranial– 14 facial

• Seven additional bones in the skull– 6 auditory ossicles– Hyoid bone

Hyoid Bone

• Suspended below the skull by ligaments

• Muscle base for the larynx (voice box)

• Supports and positions the larynx

Vertebral Column

• Spine is 26 bones– 24 vertebrae– Saccrum– Coccyx

Vertebral Column

• Vertebrae are in regions– Cervical (C1 – C7): C1 = atlas; C2 = axis– Thoracic (T1 – T12)

• Articulate with ribs

– Lumbar (L1 – L5)

• Total length in average adult is 28 inches

Intervertebral Disc

• Fibrocartilage disc that lies between two adjoining vertebrae

• Not found in sacrum or coccyx

• “Shock absorbers”

• Act as ligaments that hold the vertebrae of the spine together and as cartilaginous joints that allow for slight mobility in the spine.

• Allow for movement at the waist as they act as a pivot point and allow the lumbar spine to bend, rotate, and twist

Vertebrae Anatomy

• For the three types of vertebrae there are different distinguishing features

• The openingsof the vertebrae(foramen) form thevertebral canalwhich enclosethe spinal cord

Vertebrae Anatomy

• Vertebral foramen: opening• Vertebral arch: posterior margin of

foramen• Transverse process: site for muscle

attachment• Spinous process: Bump down your back• Body: weight-bearing portion• Lamina: roof of vertebral arch• Pedicle: walls of vertebral arch

Cervical Vertebrae

• There are seven cervical vertebrae which are located in the neck.

• They are the smallest, and lightest vertebrae of the vertebral column.

Cervical Vertebrae Anatomy

Body

Lamina

Transverse Process

Superior articular facet

Foramen

Spinous Process

Pedicle

Thoracic Vertebrae

• The rib cage of the chest is attached to the thoracic spine at each level.

• Gives a great deal of stability and support to the upper body.

• Limits the back's movement at the chest level.

Thoracic Vertebrae Anatomy

Body

Lamina

Transverse Process

Superior articular facet Foramen

Spinous Process

Pedicle

Lumber Vertebrae• There are 5 lumbar vertebrae located in the

lower back.

• Receive the most stress and are the weight-bearing portion of the back.

• Allow movements such as flexion and extensionand some lateral flexion.

Lumbar Vertebrae Anatomy

Body

Lamina

Transverse Process

Superior articular facet

Foramen

Spinous Process

Pedicle

Sacrum and Coccyx

• Sacrum: five fused vertebrae– Protects reproductive and digestive organs– Attaches axial to appendicular skeleton– Extensive muscle attachment

• Coccyx: 3-5 fused vertebrae– Attachment site for muscle that closes anal

opening

Spinal Curves

• Curved to allow for weight distribution• 2 primary curves: appear in late fetal

development– Thoracic– Sacral

• 2 secondary curves: occur months after birth– Cervical– lumbar

Spinal Curves

Primary CurveSecondary Curve

Primary CurveSecondary Curve

Chest Bones (Thorax)

• Thoracic Vertebrae

• Ribs

• Sternum

Ribs and Sternum

• 12 pairs of ribs• 7 pairs of “true ribs”

– Reach the anterior body wall and connect to the sternum by separate cartilage (costal cartilage)

• 8-12 are “false ribs”– Do not attach directly to the sternum– Costal cartilage of 8-10 fuses with 7

• Last Two pairs = “floating ribs”– No sternum connection

Sternum

• Manubrium: articulateswith the clavicle

• Body

• Xiphoid process

intervertebral disc x ray

• http://www.chirogeek.com/000_disc_anatomy.htm

• http://spanky.thehawkeye.com/features/surgery/index.html